The present invention relates to a throttle control system for an internal combustion engine, and more particularly to such a throttle control system for keeping a throttle valve open to a predetermined degree during cranking and, additionally, during a time interval subsequent to cranking.
It is known that internal combustion engines are generally difficult to start quickly and smoothly after the vehicle has run continuously for a long period of time, e.g., for 20 to 30 minutes after the engine has stopped. This difficulty arises out of the fact that the carburetor is subjected to percoration due to a high temperature of the engine causing the air-fuel mixture to be excessively rich, and such a rich air-fuel mixture cannot be ignited smoothly. Faced with such a situation, novice drivers tend to choke the engine in an attempt to get the engine started quickly, only to find themselves in greater trouble with starting the engine. There has been a need for a system which can start the engine quickly and stably even when the engine is still hot or remains cold.